Starting Questions

[rb1949]

OK, 3 components. Rebuilt starter, new solenoid, new ignition switch CYLINDER. At random unexpected times, the car will not start with the key. Turning the key does activate the solenoid plunger to click in & out, but not turn over. Leave key in 'RUN' position, jump start from battery to starter coil terminal, it turns over and fires right up. Electrical is working. Is it the solenoid or switch causing the random no start issue? Cylinder is new, "switch" is original. Could there be something defective or worn inside the switch? Yet it activates the solenoid, and makes contact to start/run via a jump. Why would the solenoid activate but not turn over with the key? My mind is blank on what to look at. Does anyone have a picture of the switch and connections? (49 Chrysler) The wires won't let me pull it down under the dash far enough to see the connections. IF needed, would an aftermarket switch wire up correctly? Have to study that. Getting rid of that goofy Armor Cable would be nice. It's only a piece of wire. I'm open for suggestions and ideas. Thanks.

[_shel_ny]

Clean, and tighten connections. Do not over tighten.

[Don Coatney]

Clean your battery terminals where the battery cables connect. Corroded dirty battery terminals can and will cause the problem you are having.

[rb1949]

I like easy suggestions. Worked fine today. Connections good. Battery & cables cleaned. Watch and wait, it was random. Thanks.

[Dodgeb4ya]

There is a critical setting of the solenoid plunger to pinion gear adjustment.

If the starter drive pinion  gear bottoms out at the starter motor housing before the solenoid plunger copper disc makes contact with the two large battery and starter winding studs

the starter won't turn over and crank.

The solenoid plunger is internally threaded for pinion gear clearance and this also affects whether or not the copper contact disc inside the solenoid reaches and makes good electrical contact with the solenoid battery stud and starter winding stud.

If the solenoid plunger does not push the copper disc firmly against the two large solenoid studs the starter motor will not turn the engine over.

That rare and very costly solenoid supposedly is new so hopefully all contacts inside it are like new and good.

I think this adjustment is almost right but not quite.

Edited September 18, 2016 by Dodgeb4ya

[greg g]

Great post!  Nice explanation. Maybe one of the mods can affix it to the tech section.  Thank.

[Niel Hoback]

Now that's the way to post an answer!

[dpollo]

There is another factor which could be at the root of the problem.   The ground for the starter relay (on top of starter) goes to the armature side of the generator which can only supply a ground when the generator is at rest.  This prevents engagement of the starter while the engine is running.   If the generator brushes are worn, it will not provide a ground (through the armature)  and the starter will be unreliable.  This problem generally occurred at about 70 000 miles when the generator brushes were up for replacement.

You will notice two wires on the ARM terminal of the regulator.  One of these goes to the generator, and the other goes to the starter relay.

[Dodgeb4ya]

The purpose of the grounding of the solenoid relay through the "ARM" stud of the generator is so that the starter cannot operate once the engine is running.

I have seen many of these Chrysler DeSoto solenoid relay's with the  blockside smaller upper stud terminal wired directly to a engine ground because of what dpollo said above.

No one took the time to diagnos the ground issue.

If the generator is charging normally there should be no relay ground issue....usually!

[rb1949]

Have to mention that since post 2 & 3, key starting has been fine. And good to see other suggestions, those kinds of tips that are probably not readily available from normal sources. Saved for reference. Thanks.

[Dodgeb4ya]

That was probably your issue to begin with. Basics Basics,